U.S. Pat. No. 4,705,849 discloses a series of technetium-.sup.99m complexes having the formula .sup.99m TcX(Y).sub.3 BR wherein X is an anion, Y is a vicinal dioxime and BR is a boron derivative. The complexes of U.S. Pat. No. 4,705,849 are prepared by a template synthesis reaction in which the ligands that are bound to the technetium atom are formed in an in-situ reaction between boronic acid, three vicinal dioximes, a halide ion, a reducing agent and pertechnetate. It has now been discovered that a novel and unexpected product is formed when the above reaction conditions are changed. These changes include the use of a new reducing agent such as triphenylphosphine which increases the yield of the new complexes of the present invention.